Update graphics/py-traitsui from 6.1.2 to 6.1.3.
Remove a test exclusion as the test was corrected upstream.
QA (120Ramd64, py36):
port test: OK
make test: OK
portlint gives a false positive as before:
$ portlint -Ca
WARN: Makefile: When USES=pyqt:5 is defined, you must also define
0 fatal errors and 1 warning found.